1. Field of the Invention
The present invention relates to a mounting and demounting device of an optical unit for use with interchangeable optical instruments, which device is used for mounting and demounting of an interchangeable optical instrument such as an interchangeable lens on and from a body proper of the optical unit.
2. Description of the Prior Art
A camera of lens interchangeable type is provided with a positioning member for positioning an interchangeable lens in place on the camera body and locking the interchangeable lens at a predetermined angular position. This positioning member is constantly urged by a spring in a projecting direction, hence the normal mounting operation cannot be proceeded with unless the interchangeable lens is pushed against a mount face spring of the camera body with a force enough to overcome such spring urge over the entire moving stroke of the positioning member. This is disadvantageous in that turning the interchangeable lens forcibly with an insufficient pushing force applied toward the camera body will possibly cause damage to bayonet pawls for mounting. Additionally, keeping the positioning member pressed with a sufficient force during a mounting and demounting operation is unpleasant or even painful to the camera user. Moreover, when mounting an interchangeable lens to the camera body or demounting it therefrom, a strong contact takes place between the positioning member and a mounting face of the interchangeable lens to possibly cause damage to either or both thereof.
With an auto-focusing camera in which a drive means for focusing includes a driving shaft interlocked with the positioning member with a given positional relationship and engageable with a driven shaft on the side of an interchangeable lens, there is a possibility that, when an interchangeable lens is mounted in haste, etc., the positioning member fails to be properly engaged in a mating groove on the interchangeable lens side, being half-inserted. Should it occur, the driving shaft and the driven shaft on the camera side and the interchangeable lens side cannot be properly engaged either. In order to cope with such an unfavorable condition, it is required to further strengthen the spring urge for the positioning member in a camera of this type and the abovementioned disadvantages become more remarkable.